The present invention relates to a ball valve. More particularly, the present invention relates to a ball valve with a dual seat arrangement which is effective at maintaining a seal when pressure is acting from above and/or below the system.
A number of oilfield operations involve the use of apparatus which includes a ball valve. A ball valve generally includes a ball seat for receiving a sealing ball. Such operations include subsurface flow control operations, completions and interventions.
Once a ball valve is closed by the seating of the ball on the ball seat, it is essential that an effective seal is maintained. This is particularly important when the ball valve is subjected to high downhole temperatures and high downhole pressures.
Prior art sealing systems for ball valves, such as that disclosed in U.S. Pat. No. 5,865,246, use a single point to provide sealing and may not provide consistent sealing results.
A sealing system described below provides more consistent sealing, particularly at high temperatures and pressures, by the use of a dual seal arrangement situated above and/or below the ball to effect sealing from pressure acting both above and below a ball of the system. The ball maintains a consistent seal regardless of whether pressure is applied from above the ball, below the ball or from both above and below the ball. Thus, the dual seal arrangement of the system described below provides a reliable, bidirectional seal point which is particularly suitable for use in apparatus which is located in a high temperature, high pressure environment.
The system described below may be used in conventional ball valves, particularly ball valves such as the LV lubricator valve, the FSl fluid loss device and the IB series of fluid loss devices, all manufactured by Halliburton Energy Services, Inc.